Multi-agent logic for reasoning about duties and powers in private law
Tianwen Xu, Fengkui Ju · 2023
Duties and powers are two fundamental notions in private law. In this work, we provide our conception of duties and powers and present a logic for reasoning about them. We treat duties as agents' obligations towards others to perform actions. We think that powers are agents' legal abilities, conferred by law, to change legal positions between agents. How to exercise powers is also specified by law. Many factors, including the exercise of powers, fulfillment of duties, violation of duties, and factual changes in the world, can change duties. The ontic level of the logic is a multi-agent dynamic logic, where agents have abilities to change atomic facts. At its normative level, agents have duties towards others to change atomic facts, and have powers to change duties by changing atomic facts. When agents behave, the ontic and normative aspects of the world change accordingly. The implications of the formalization are studied extensively.